The present invention relates to a telephonic data access and transmission system, and, more particularly, to a system for transmitting and accessing data through a standard TOUCH-TONE telephone system utilizing a standard TOUCH-TONE telephone set.
In the past, several systems have been proposed which allow data to be entered into a telephone TOUCH-TONE set and which then transmit the data to a central computer or the like. It is typical for such systems to rely on coding schemes wherein strings of letters may be transmitted to the central computer through the TOUCH-TONE telephone set by depressing TOUCH-TONE keys in such a manner that the central computer will be able to interpret the information transmitted. Such systems are desirable for use in conducting business transactions by phone without intervention beween the caller and the data processing apparatus. For example, it is desirable to conduct banking by phone, to purchase commercial products by phone, place reservations on airlines or the like by phone and arrange ticketing. Further, it would be convenient for a telephone user to gain access to various informational data bases or the like. For instance, it is desirable for a telephone user to get phone directory information.
Although it is desirable to tramsit data and access data utilizing the TOUCH-TONE (DTMF) transmitter of the standard telephone set, systems devised by the prior art are inefficient because of the complicated coding schemes which are involved. Coding schemes have been necessary in the past because the standard telephone TOUCH-TONE key pad is designed to provide only ten or twelve distinct keys. In order to transmit letters, prior art systems have relied on coding schemes and translating devices to transmit information between the telephone set and the computer.
The standard TOUCH-TONE telephone set (transmitter) typically includes twelve buttons, or keys, disposed in a matrix of four horizontal rows by three vertical columns. Each of the keys has associated therewith two distinct frequencies: A frequency chosen from a group (`A`) of relatively low frequencies, corresponding to the row wherein the button is disposed; and a frequency selected from a group (`B`) of relatively high frequencies, corresponding to the column wherein the button is disposed. Depression of a given key causes transmission of a dual tone multi frequency (DTMF) signal having frequency components of both the group A (row) and group B (column) frequencies associated with the disposition of the key in the matrix.
Each key of the TOUCH-TONE phone additionally is enscribed with indicia such as numerical designations (0 through 9) as well as alphabetic designations (A through Z) as shown in FIG. 1. The alphabetic characters "Z" and "Q" are not portrayed on the standard TOUCH-TONE set, but can be considered to be associated with the keys with the designations 9 and 7 respectively.
U.S. Pat. No. 4,427,848 issued to Tsakanikas teaches a system for the transmission of alpha numeric data by use of a standard telephone set. The system provides a translation technique wherein alphabetic characters are transmitted by depressing a designated key a number of times equal to the relative position of the inscription of the character on the key, followed by the depression of a key on which the character is inscribed. A return to the numeric mode may be effected by depression of a second designated key. Other translation schemes are disclosed by Tsakanikas and are equally burdensome to a user.
U.S. Pat. No. 4,500,751 issued to Darland et al, teaches a data communication system wherein a large number of remote terminals communicate with a central host terminal through telephone lines. The system contemplates the use of two or more twelve-key TOUCH-TONE key pads which are connected to the same inputs of a two tone signal generator. Key pads are differentiated when the group of keys in each key pad triggers a corresponding timer when the key is released. The timer then actuates a signal generator through one of its inputs to generate a tone that identifies which key pad is being actuated when the key in that pad is released.
U.S. Pat. No. 4,307,266 issued to Messina teaches a telephone communication apparatus for use by a handicapped person. The system uses a code wherein the user enters the appropriate position for the letter of the alphabet to be communicated and a second entry is input to identify which one of the plurality of letters (or the number) the user intends to transmit.
U.S. Pat. No. 4,012,599 issued to Meyer teaches a telephone communication system for use by a deaf person. An encoding scheme is utilized wherein alphabetic characters are trnsmitted by activating at least two keys.
U.S. Pat. No. 3,381,275 issued to Tsakanikas, describes a telephonic data transmission system utilizing what is termed a twin depression translation technique. This system involves the simultaneous depression of a plurality of keys which produces a signal having frequency characteristics, which may be discriminated from the pairs of frequencies generated in response to the depression of a single key.
Another example of a TOUCH-TONE to alpha numerical translator is described in U.S. Pat. No. 3,618,038 issued to Stein. This system utilizes what is known as the delayed depression translation technique, wherein depression of keys having different durations are discriminated.
In addition, other translation techniques whereby each alpha numeric symbol is represented by a specific sequence of DTMF signals with each character separated by a specific designated DTMF signal have been proposed. An example of such a transmission technique is described in Brumfield et al, Electronics, "Making a Data Terminal out of the TOUCH-TONE Telephone" McGraw Hill, July 3, 1980.
As is apparent from the above discussion, systems taught by the prior art are slow, involve a coding scheme which is difficult for a user to master, and are in general not practical for most people to use.